HYDRAULIC VALVE

Abstract

A hydraulic valve includes a valve housing, a valve cone, a spring housing, a check valve, a first hydraulic connection and a second hydraulic connection. The valve housing has a valve seat and the valve cone is movable in the valve housing between a closed position and an open position. In the closed position, the valve cone is in contact with the valve seat and blocks a first flow path between the first and the second hydraulic connection. In the open position, the valve cone is lifted off the valve seat and the first flow path is opened. A spring element is disposed in the spring housing, which biases the valve cone into the closed position. The check valve is disposed in the valve cone and opens a second flow path from the second hydraulic connection to the first hydraulic connection when pressure is applied to the second hydraulic connection.

Claims

1. A hydraulic valve, comprising: a valve housing; a valve cone; a spring housing; a check valve; a first hydraulic connection; and a second hydraulic connection, wherein the valve housing comprises a valve seat, wherein the valve cone is movably disposed in the valve housing between a closed position and an open position, wherein the valve cone abuts the valve seat in the closed position and blocks a first flow path between the first hydraulic connection and the second hydraulic connection, wherein the valve cone is lifted off the valve seat in the open position and opens the first flow path from the first hydraulic connection to the second hydraulic connection, wherein a spring element is disposed in the spring housing, wherein the spring element biases the valve cone into the closed position, and wherein the check valve is disposed in the valve cone and, when pressure is applied to the second hydraulic connection, opens a second flow path from the second hydraulic connection to the first hydraulic connection, wherein the valve cone has a fluid guide passing through the valve cone upstream of the check valve as viewed in the direction of flow from the second hydraulic connection to the first hydraulic connection, the fluid guide being part of the first and/or the second flow path.

2. The hydraulic valve according to claim 1, wherein the spring housing includes the second hydraulic connection.

3. A hydraulic valve, comprising: a valve housing; a valve cone; a spring housing; a check valve; a first hydraulic connection; and a second hydraulic connection, wherein the valve housing comprises a valve seat, wherein the valve cone is movably disposed in the valve housing between a closed position and an open position, wherein the valve cone abuts the valve seat in the closed position and blocks a first flow path between the first hydraulic connection and the second hydraulic connection, wherein the valve cone is lifted off the valve seat in the open position and opens the first flow path from the first hydraulic connection to the second hydraulic connection, wherein a spring element is disposed in the spring housing, the spring element biasing the valve cone into the closed position, wherein the check valve is disposed in the valve cone and, when pressure is applied to the second hydraulic connection, opens a second flow path from the second hydraulic connection to the first hydraulic connection, wherein the spring housing comprises the second hydraulic connection, an external thread for screwing the hydraulic valve into a block, and a sealing member disposed on the outer periphery of the spring housing, wherein the sealing member is disposed in axial direction between the external thread and the valve housing.

4. The hydraulic valve according to claim 3, wherein the valve cone has a fluid guide passing through the valve cone upstream of the check valve as viewed in the direction of flow from the second hydraulic connection to the first hydraulic connection, the fluid guide being part of the first and/or the second flow path.

5. The hydraulic valve according to claim 1, wherein the valve cone has an axially extending receiving space, the fluid guide comprising at least one bore extending from the outer surface of the valve cone to the receiving space.

6. The hydraulic valve according to claim 5, wherein the check valve is disposed in the receiving space.

7. The hydraulic valve according to claim 1, wherein the valve housing comprises a fluid chamber, the fluid chamber being part of the first flow path, and the fluid guide opens into the fluid chamber at least in the open position of the valve cone.

8. The hydraulic valve according to claim 7, wherein the valve housing has an axial bore with an inner circumferential surface for receiving the valve cone, the fluid chamber being formed by an at least partially circumferential recess on the inner circumferential surface of the axial bore.

9. The hydraulic valve according to claim 1, wherein the valve cone has a spring housing end facing the spring housing, the valve cone being guided in the valve housing between the spring housing end and the fluid guide.

10. The hydraulic valve according to claim 1, wherein the hydraulic valve has a spring plate disposed in the spring housing, the spring plate has an axial passage, and the valve cone abuts against the spring plate.

11. The hydraulic valve according to claim 1, wherein the hydraulic valve has a third hydraulic connection, wherein a control pressure is applicable to the third hydraulic connection in order to move the valve cone into the open position counter to a force of the spring element, the hydraulic valve having a control piston acting on the valve cone, wherein pressure to the control piston is applicable via the third hydraulic connection.

12. The hydraulic valve according to claim 1, wherein the hydraulic valve is a load holding valve.

13. The hydraulic valve according to claim 5, wherein the fluid guide includes a plurality of bores.

14. The hydraulic valve according to claim 3, wherein the hydraulic valve is a load holding valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a section through a hydraulic valve according to a first embodiment, with the valve cone in the closed position and the check valve open;

[0026] FIG. 2 is a detailed view of the hydraulic valve shown in FIG. 1;

[0027] FIG. 3 is the hydraulic valve according to FIG. 1, with the valve cone in the open position and the check valve closed;

[0028] FIG. 4 is a detailed view of the hydraulic valve shown in FIG. 3; and

[0029] FIG. 5 is a section through a hydraulic valve according to a second embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

[0030] FIGS. 1 to 4 depict a hydraulic valve 1 configured as a load holding valve according to a first embodiment of the present invention. As shown, the load holding valve 1 is configured as a load holding valve cartridge which is screwed into a block B. Such a load holding valve cartridge 1 is used, for example, to control a hydraulic cylinder or other hydraulic consumer against a load, to lower it in a controlled manner under load according to a predetermined quantity characteristic (pressure difference across the load holding valve 1 over the quantity or volume flow) with a control pressure and a predetermined control behavior, and to keep the load free of leakage in the non-actuated state.

[0031] For this purpose, the load holding valve cartridge 1 has a valve housing 2 with a valve cone 3 axially movable therein, a first hydraulic connection 6 and a second hydraulic connection 7. Furthermore, the load holding valve cartridge 1 has a spring housing 4 with a spring element 9 disposed therein. On the one hand, the spring element 9 is supported on a first spring plate 18 arranged axially movably in the spring housing 3. On the other hand, the spring element 9 is supported on a second spring plate 22 fixed in the spring housing. The preload of the spring element 9 can be adjusted by moving the second spring plate 22 in a known manner by screwing it in and out along the spring housing 4. The preload force of the spring element 9 is transmitted via the first spring plate 18 to a spring housing end 17 of the valve cone 3, so that the latter is preloaded to the closed position SS shown in FIG. 1.

[0032] The spring housing 4 has an external thread 23 for screwing the spring housing 4 into the block B. A sealing member 24 is provided to prevent hydraulic fluid under high pressure from escaping along the external thread 23. As shown in particular in FIG. 2 and FIG. 4, the sealing member 24 is formed as a sealing ring which is received in a corresponding receiving groove 30 on the outer circumference of the spring housing 4. In this exemplary embodiment, the sealing ring 24 is an O-ring. Seen in the axial direction from the second hydraulic connection 7 to the valve housing 2, the sealing member 24 is arranged downstream of the external thread 23 i.e., in the screwed-in state of the load holding valve cartridge 1 in the block B between the external thread 23 and the valve housing 2. In this way, it can be ensured that the structurally weaker point of the spring housing 4 due to the receiving groove 30 is largely not subjected to any tensile load even in the event of an unintentional external force acting on the spring housing 4, and the risk of the spring housing 4 tearing off at this point is eliminated.

[0033] As shown in FIG. 1 and FIG. 3, the second hydraulic connection 7 is disposed at the axial end of the spring housing 4 facing away from the valve cone 3. The first hydraulic connection 6 is connected in a conventional manner to a channel in the block B. A hydraulic consumer, for example a hydraulic cylinder, which can be extended and retracted against a load, is regularly connected to the first hydraulic connection 6. At the second hydraulic connection 7, for example, a pressure source, a spool valve or a shuttle valve is connected in a conventional manner. In the closed position SS shown in FIG. 1, the load holding valve cartridge 1 is not actuated and a load applied via the hydraulic cylinder connected to the first hydraulic connection 6 is held free of leakage, since the valve cone 3 rests against a valve seat 8 formed on the valve housing 2 and blocks a first flow path between the first hydraulic connection 6 and the second hydraulic connection 7, as will be described in more detail below.

[0034] To lift a load via the hydraulic cylinder connected to the first hydraulic connection 6, the first hydraulic connection 6 must be pressurized. For this purpose, the load holding valve cartridge 1 has a check valve 5 bypassing the valve seat 8 to open a second flow path from the second hydraulic connection 7 to the first hydraulic connection 6.

[0035] The check valve 5 is received in an axially extending receiving space 11 of the valve cone. As shown, the check valve 5 is configured as a ball check valve and comprises a ball 26 which, in the closed position of the check valve 5, rests against a check valve seat 27 formed in the receiving space 11 of the valve cone 3, cf. also FIG. 3. The ball 26 is supported on a cup 28 in which a spring element 29 is received. The spring element 29 generates a relatively small force which is transmitted to the ball 26 via the cup 28 and ultimately serves only to hold the ball 26 in a pressure-free state against the check valve seat 27. When pressure is applied to the second hydraulic connection 7, the ball 26 is displaced axially against the closing force of the spring element 29 due to the pressure then present in the receiving chamber 11, so that the ball 26 is lifted off the check valve seat 27, cf. FIG. 1 and FIG. 2. The hydraulic fluid can then flow from the receiving chamber 11 to the first hydraulic connection 6 along the second flow path and the hydraulic cylinder connected there extends. The load is lifted.

[0036] In a condition in which a load is held free of leakage, the load pressure applied through the first hydraulic connection 6 also acts on the ball 26 so that it safely abuts against the check valve seat 27.

[0037] For controlled lowering of the load, the first hydraulic connection 6 must be connected to the second hydraulic connection 7. For this purpose, the valve cone 3 is moved from the closed position SS shown in FIG. 1 to the open position OS shown in FIG. 3. For this purpose, the valve cone is lifted from the valve seat 8 formed on the valve housing 2 against the preload force of the spring element 9 and the first flow path between the first hydraulic connection 6 and the second hydraulic connection 7 is released in order to lower the load in a controlled manner.

[0038] In order to move the valve cone 3, the valve housing 2 in this embodiment has a third hydraulic connection 20, via which a control pressure can be applied. The control pressure applied to the third hydraulic connection 20 acts on a control piston 21 of the load holding valve cartridge 1. In this exemplary embodiment, the control piston 21 is formed integrally with the valve cone 3 so that pressurization of the third hydraulic connection 20 with a correspondingly high control pressure (i.e., that the total pressure of open-loop pressure and open-loop pressure is higher than the total pressure of the valve cone 3) is possible. (i.e., the total pressure from the control pressure and the load pressure exceeds the preload force of the spring element 9) moves the control piston 21 together with the valve cone 3 axially in the direction of the spring housing 4, so that the valve cone 3 is lifted from the valve seat 8.

[0039] In the open position OS of the valve cone 3 i.e., when the third hydraulic connection 20 is pressurized, hydraulic fluid can flow from the first hydraulic connection 6 to the second hydraulic connection 7 along the first flow path. Here, the hydraulic fluid first enters an axial bore 15 of the valve housing 2 via the first hydraulic connection 6 and flows past the valve seat 8 into a fluid chamber 14. In this exemplary embodiment, the fluid chamber 14 is formed as a circumferential groove on an inner circumferential surface 16 of the axial bore 15. The valve cone 3 has a fluid guide 10 with a plurality of bores 13 penetrating through the valve cone 3 by extending from the outer surface 12 of the valve cone 3 into the receiving chamber 11. As shown, the fluid guide 10 is provided upstream of the check valve 5 as viewed in the flow direction from the second hydraulic connection 7 to the first hydraulic connection 6. In this embodiment, the bores 13 are each grouped, and provided on the valve cone 3 so as to connect the main flowed regions of the fluid chamber 14 to the receiving chamber 11. The hydraulic fluid then flows from the fluid chamber 14 via the bores 13 of the fluid guide 10 into the receiving chamber 11 and from there in the direction of the second hydraulic connection 7. In order to ensure a flow as unhindered as possible, the first spring plate 18 comprises a relatively large axial passage 19.

[0040] In order to achieve particularly good guidance of the valve cone 3, the valve cone 3 is guided between the spring housing end 17 and the fluid guide 10 in the valve housing 2. As shown in particular in FIG. 2 and FIG. 4, the valve cone 3 is guided on a corresponding guide surface which, viewed from the first hydraulic connection 6 to the fluid chamber 14, is formed downstream of the fluid chamber 14 on the inner circumferential surface 16 of the axial bore 15.

[0041] In FIG. 5, a second exemplary embodiment of a hydraulic valve 101 configured as a load holding valve cartridge according to the invention is shown. The hydraulic valve 101 according to the second embodiment differs from the hydraulic valve 1 described above in the configuration of the second hydraulic connection 107. As shown, the second hydraulic connection 107 is not formed on the spring housing 104, but on the valve housing 102. The second hydraulic connection 107 is connected to a corresponding channel in the block B. In this embodiment, the fluid guide 110 of the valve cone 103 comprises two bores 113 extending from the outer surface 112 of the valve cone 103 into the receiving space 111 of the valve cone 103.

[0042] To lift the load via the hydraulic cylinder connected to the first hydraulic connection 106, pressure is applied to the second hydraulic connection 107. The hydraulic fluid then flows at least partially through the bores 113 of the fluid guide 110 into the receiving chamber 111 and opens the check valve 105. The hydraulic fluid then flows directly to the first hydraulic connection 106 and the load is lifted.

[0043] To lower the load, the valve cone 103 is moved in a controlled manner against the biasing force of the spring element 109 to the open position so that the valve cone 103 lifts off the valve seat 108. Hydraulic fluid can then flow from the first hydraulic connection 106 inside the valve housing 102 along the valve cone 103 to the second hydraulic connection 107.

[0044] It should be noted that the above embodiments are indeed described for a hydraulic valve configured as a load holding valve cartridge. However, the advantages of the invention are also applicable to other types of hydraulic valves, for example, pressure relief valves, check valves, load holding valves which are not designed as a cartridge, or stop valves.

LIST OF REFERENCE SIGNS

[0045] 1, 101 hydraulic valve/load holding valve/load holding valve cartridge [0046] 2, 102 Valve housing [0047] 3, 103 valve cone [0048] 4, 104 spring housing [0049] 5, 105 check valve [0050] 6, 106 first hydraulic connection [0051] 7, 107 second hydraulic connection [0052] 8, 108 valve seat [0053] 9, 109 spring element [0054] 10, 110 fluid guide [0055] 11, 111 receiving chamber [0056] 12, 112 outer surface of the valve cone [0057] 13, 113 bore [0058] 14 fluid chamber [0059] 15 axial bore [0060] 16 inner circumferential surface of the axial bore [0061] 17 spring housing end [0062] 18 first spring plate [0063] 19 axial passage [0064] 20 third hydraulic connection [0065] 21 control piston [0066] 22 second spring plate [0067] 23 external thread [0068] 24 sealing member [0069] 26 ball [0070] 27 check valve seat [0071] 28 cup [0072] 29 spring element [0073] 30 receiving groove [0074] B block [0075] OS open position [0076] SS closed position